RE: tracing memory allocation sizes

From: Noveljic Nenad <nenad.noveljic_at_vontobel.com>
Date: Mon, 25 Nov 2019 12:35:26 +0000
Message-ID: <21745_1574685340_5DDBCA9C_21745_4645_1_b4230463261c49ccb04f05121324c1a3_at_vontobel.com>



Thanks, Tanel.

The requested size seems to be passed through the rdx register (3rd argument):

  44  -> kghalf                                (joxu pga heap(7fffbd7b4e48) bytes: 203128887
  44    -> kghalo                              (joxp heap(7fffbd9a9d40), "joxu pga heap") bytes: 203128928
  44      -> kghalo                            (pga heap(7fffbdb82310), "joxp heap") bytes: 203128968
  44        -> mmap                            bytes: 203161600
  44        <- mmap                              44        -> mmap                            bytes: 203161600
  44        <- mmap                              44      <- kghalo                            = 7fffb0703f78
  44    <- kghalo                              = 7fffb0703fa0
  44  <- kghalf                                = 7fffb0703fc8

The memory allocated by mmap is somewhat larger than requested, because it’s ceiled to the next 64k size for pga allocations (in the function kgh_invoke_alloc_cb, I think).

The output above is produced by your script which I modified to include mmap calls as well. On top of that, I print arg2 when entering the kgh* functions.

Best regards,

Nenad

https://nenadnoveljic.com/blog/

From: Tanel Poder <tanel_at_tanelpoder.com> Sent: Samstag, 16. November 2019 21:19
To: Noveljic Nenad <nenad.noveljic_at_vontobel.com> Cc: ORACLE-L (oracle-l_at_freelists.org) <oracle-l_at_freelists.org> Subject: Re: tracing memory allocation sizes

Hi,

Back when I was doing such heap allocation tracing for memory leak research with DTrace on Solaris, I wrote this script to extract the allocation comments:

https://github.com/tanelpoder/tpt-oracle/blob/master/dtrace/trace_kghal.sh

The offsets may differ across platforms and DB versions, but I'd imagine that the size somewhere behind that *arg1 pointer too.

--
Tanel Poder
https://blog.tanelpoder.com/seminar

On Thu, Nov 14, 2019 at 7:49 AM Noveljic Nenad <nenad.noveljic_at_vontobel.com<mailto:nenad.noveljic_at_vontobel.com>> wrote: Does anybody know how to extract the requested and allocated memory size from the parameters and return values, respectively, of the functions kghalf, kghalo and kghalp?

Best regards,

Nenad

https://nenadnoveljic.com/blog/



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Received on Mon Nov 25 2019 - 13:35:26 CET

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